The invention relates generally to belt-conveyor checkweighers and product diverters.
In many production lines, conveyed products are weighed by checkweighers, and the weights used to grade, batch, label, price, or check product quality or uniformity. Checkweighers are typically located in a conveyor line so that they can weigh the products “in line” and possibly also “in motion,” i.e., without stopping product flow. A conventional checkweigher comprises a short length of conveyor belt running atop a scale table that freely supports the belt and the conveyed products on the belt while making a weight measurement. Often, products are fed onto the checkweigher by a gapping conveyor that accelerates the products to pull a gap between consecutive products. In that way only one product at a time rests on the checkweigher's scale. Once weighed, a product transfers to a reject, grading, or other selective diverting conveyor for proper dispositioning according to the product's weight. Common diverters use pneumatic pusher arms, paddle arms, air blasts, or tilting conveyers to divert products to their proper destinations.
One of the problems with conventional systems as described is that there are four product transfers across gaps between sequential conveyor elements: (1) transfers onto the gapping belt; (2) transfers from the gapping belt to the checkweigher belt; (3) transfers from the checkweigher belt to the diverting conveyor; and (4) transfers off the diverting conveyor to downstream handling. Each of these transfers can jostle the product, causing it to change its orientation and perhaps cause a jam on the production line. If orientation is important—as it often is—the product has to be “styled” back to its original orientation if the jostling is too great. Furthermore, paddles or pushers can mar product labels.